The invention relates to a surgical device for removing obstructive and/or protrusive material from a lumenal passage or cavity within the human body. More particularly, the invention relates to surgical devices which core, homogenize, dilute, and aspirate stenotic or protrusive material. Within the vascular system, the invention relates to atherectomy devices for removing atheromatous and other stenotic material from arteries or to valvectomy devices for removing valves from veins. In other segments of the body, the invention relates to biopsy devices for cutting and removing unwanted materials, projections or outgrowths from various cavities of the body such as the nasal cavity, the synovial cavity and cavum epidural. For clarity and simplicity, the invention will be presented as it relates particularly to atherectomy, though applications to other uses will become evident.
An atherectomy device is a device for surgically removing atheromatous and other stenotic material from blood vessels. The performance of an atherectomy can be a useful therapeutic modality for treating occlusive arterial diseases. A number of vascular catheters have previously been developed to facilitate the surgical removal of such obstructive material. For example, one such prior vascular catheter includes a coring device fitted onto its distal end. To remove the obstructive material, the vascular catheter is percutaneously inserted into a blood vessel and guided to the obstructed area by means of medical imaging. Once the obstructed area is reached, the coring device is urged into the obstructive material so as to core through it. If the quantity of obstructive material is relatively small, the obstructive material may be removed by simply withdrawing the catheter. However, if the quantity of obstructive material exceeds the capacity of the coring device, it may be necessary to insert and withdraw the vascular catheter repeatedly. The repeated insertion and withdrawal of a vascular catheter has the potential of damaging the blood vessel and is considered to be medically undesirable.
It has been found that, under some circumstances, cored material may be removed from the vascular catheter by means of aspiration. A coring atherectomy device which includes an aspiration feature for continuously removing cored material is described by Marangoni et al. (U.S. Pat. No. 4,772,258). Marangoni describes a vascular catheter having an aspirating lumen for removing cored material without withdrawing the catheter from the blood vessel. Marangoni discloses that this same lumen can also house a flexible shaft for rotationally driving the coring device so as to facilitate the coring and removal of occlusive material.
Other references disclose that the aspiration process can be improved if the obstructive material is agitated and broken up during the aspiration process. Husted (U.S. Pat. No. 4,754,755) discloses an atherectomy device which agitates and breaks up cored material within the aspiration lumen of the catheter. Husted's coring device is rotationally driven by a wire housed within the aspiration lumen of the catheter. When the wire is rotated, it agitates and breaks up the obstructive material within this aspiration lumen.
It has also been found that the aspiration process can be improved if the occluded area is irrigated while it is being cored. A coring atherectomy device which
simultaneously irrigates and aspirates is disclosed by Shiber (U.S. Pat. No. 4,819,634). Shiber's device includes a rotatable hollow tube attached to the coring device and housed within the lumen of the catheter. This rotatable hollow tube serves both as a conduit for aspiration and as a rotational drive for the coring device. Irrigation fluid is conducted to the obstructed site through the lumen of the catheter, i.e. through an annular channel formed by the inner wall of the catheter and outer wall of the rotatable hollow tube. As obstructive material is cored, irrigation fluid is expressed into the blood vessel where it may then be aspirated in conjunction with the aspiration of cored obstructive material into the rotatable hollow tube.
It has also been shown that a hole can be drilled through obstructive material or other stenotic material within a blood vessel and that the drilled material may be irrigated and aspirated away. Moss (U.K. Patent No. 1,235,321) discloses a vascular catheter which contains a transverse blade. The transverse blade is rotationally driven by a hollow tube housed within the lumen of the catheter. Irrigation fluid is conducted to the obstructed site through the hollow tube. As a hole is drilled through the obstructive material, the irrigation fluid and shaving of obstructive material can be aspirated through the lumen of the catheter, i.e. through a space between the outer wall of the hollow tube and the inner wall of the catheter.